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<?php
/**
* Hoa
*
*
* @license
*
* New BSD License
*
* Copyright © 2007-2017, Hoa community. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the Hoa nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS AND CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
namespace Hoa\Graph\Iterator;
use Hoa\Graph;
use Hoa\Iterator;
/**
* Class \Hoa\Graph\Iterator\BreadthFirst.
*
* Iterate over the graph with the Breadth-First search algorithm, starting
* from a specific node.
*
* @copyright Copyright © 2007-2017 Hoa community
* @license New BSD License
*/
class BreadthFirst extends Generic implements Iterator\Aggregate
{
/**
* Iterator over the graph with the Breadth-First Search algorithm.
*
* @return \Generator
*/
public function getIterator()
{
$graph = $this->getGraph();
$startingNode = $this->getStartingNode();
$queue = [$startingNode];
$visited = [];
yield $startingNode;
$visited[$startingNode->getNodeId()] = true;
while (!empty($queue)) {
$node = array_pop($queue);
foreach ($this->getNeighbours($node) as $child) {
if (isset($visited[$child->getNodeId()])) {
continue;
}
yield $child;
$visited[$child->getNodeId()] = true;
array_unshift($queue, $child);
}
}
}
/**
* Get neighbours of a specific node.
*
* @return array
*/
public function getNeighbours(Graph\Node $node)
{
return $this->getGraph()->getChildren($node);
}
}
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